Preparation And Research Of Polyurethane Modified Cashew Phenolic Resin Anticorrosive Coating

Phenolic resin coating has the advantages of high coating hardness,good insulation,wear resistance and chemical corrosion resistance,but the traditional phenolic resin coating is not used alone in many projects because of its high brittleness and easy cracking.In order to improve the comprehensive performance of phenolic resin coatings,they are usually modified to improve toughness and corrosion resistance.In this paper,cardanol furfural resin coating was prepared by using cheap renewable resources cardanol and furfural instead of petroleum-derived phenolic aldehyde.The effects of reaction temperature,reaction time,catalyst addition and molar ratio of phenolic aldehyde on the performance of the coating were studied.The preparation of polyurethane prepolymer and the study of modified phenolic resin were carried out.(1)Firstly,cashew phenol instead of phenol and furfural instead of formaldehyde were used as raw materials to prepare thermosetting phenolic resin coating under the action of alkaline catalyst and phenolic aldehyde molar ratio less than 1.The effects of reaction temperature and reaction time on the film properties were discussed.The structure of cardanol furfural resin was characterized by infrared spectroscopy.The thermal stability of the coating film was analyzed by thermogravimetry.According to the national standard,its basic coating properties,mechanical properties and corrosion resistance were tested.The results show that the optimum technological conditions for preparing the cardanol furfural resin anticorrosive coating are as follows: the temperature is 90?,the reaction time is 90 ? 120 min,and the anticorrosive coating prepared under this condition has the best film performance.(2)Under the same reaction temperature and reaction time,the effects of different molar ratios of phenolic aldehyde on the viscosity,solid content,film properties and heat resistance of the coating were discussed.The results show that the molar ratio of phenolic aldehyde suitable for reaction is 1: 1.5 ? 1: 1.7,of which 1: 1.6 is the best,and the film properties and heat resistance of the synthesized cardanol furfural resin are the best.(3)Polyether polyose and diphenylmethane diisocyanate(MDI)are used to prepare polyurethane prepolymer with R value(NCO/OH mass ratio)of 2,and the polyurethane prepolymer is modified to cardanol furfural resin coating by blending modification method.The optimal formula of the modified cardanol furfural resin coating is determined by studying the influence of the amount of polyurethane prepolymer on a series of properties of the modified cardanol resin coating,such as the viscosity,leveling,mechanical properties,corrosion resistance and the like.The research results show that through the above-mentioned performance tests on six groups of anti-corrosive coatings with different polyurethane prepolymer content(0%,5%,10%,15%,20%,25%),it was found that At%,the coating mechanical properties are significantly improved;when the prepolymer content is 20%,the coating has the best corrosion resistance.Comprehensive analysis shows that when the content of the polyurethane prepolymer used in the blending modification is 20%,the performance of the anticorrosive coating can reach the best.